<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<script>

    var arr=[1,2,3,3,3,4,6];
    var arr1=[];
    for(let i=0;i<arr.length;i++){
        if(arr1.indexOf(arr[i])<0){
            arr1.push(arr[i])
        }
    }
    console.log(arr1)

</script>

</body>
</html>